Retaining walls or freestanding walls can be made of natural stone, such as quarried stone. However, due to the irregular shape and size of natural stone or quarried stone, significant time and skill is required in erecting a wall from natural stone. The assembly of a curved natural stone wall is particularly difficult. Using quarried stone of ashlar dimensions facilitates the assembly of a natural stone retaining wall, but still requires significant time and skill, unless the stones are all cut to common dimensions, to allow the stones to be stacked in regular rows. Trimming natural stones to allow for the assembly of a curved wall is particularly time consuming and costly.
The use of artificial blocks made of concrete has greatly facilitated the assembly of retaining walls, but the appearance of such walls is very even and in general less appealing than that of a natural stone wall. Split concrete blocks and surface treated concrete blocks have been used to simulate the appearance of natural stone, but are still easily distinguished from natural stone walls.
Artificial facing panels and paving stones with an appearance resembling natural stone, such as ledgestone, fieldstone or quarried rock are known in the art. Natural stone, in particular chipped or broken stone, such as quarried stone, has recognizable appearance characteristics. Generally, natural stone includes at least one facing surface with randomly dispersed projections, depressions, crevices, cracks and the like. Moreover, the natural appearance of the stone is further caused by the irregularity of the broken outer edge, contour, or periphery of that facing surface. Facing panels for adhesive application to an existing wall structure and having the appearance of natural stone are shown in U.S. Pat. No. 5,535,563. A cast paving stone having an upper part with a surface structure simulating the appearance of natural stone is disclosed in U.S. Pat. No. 4,627,764. EP 0666372 discloses a concrete paving stone with a facing surface having embossed therein the desired visual impression of natural stone. The face of the concrete block disclosed in EP 0666372 is formed with an irregular edge and the side surfaces have an irregularly corrugated profile. The front surface or face surface is cast to resemble natural stone such as ledgestone.
Concrete blocks are known for the use in landscaping applications, particularly for retaining walls. Various different block configurations or shapes are known. To allow the assembly of curved walls, concrete retaining wall blocks are usually provided with a rearwardly tapered body with sidewalls that are at an angle of less than 90 degrees to the front face of the block. Stacking such blocks side by side with the angled sidewalls of adjacent blocks engaging one another results in a convexly curved wall. Concave curvatures are obtained by stacking the blocks side by side with the front edges touching, while the tapered rear ends are spaced apart. This provides significant flexibility in the creation of curved walls the radius of curvature of the wall being limited solely by the angle of the sidewalls relative to the front face. However, tapered blocks and walls built with such blocks have several drawbacks. Curved walls with a radius of curvature smaller than the minimum radius set by the angle of the sidewall taper will have gaps in the front face. Moreover, molding dry cast tapered blocks with converging sidewalls and an embossed front face is challenging due to the need for stripping the compressed block from the mold.
Dry casting uses a no slope concrete mixture which is filled into a mold cavity and compressed to sufficiently pre-consolidate the block to permit handling of the block prior to curing of the concrete mixture. After pre-consolidation, the block is stripped from the mold and transported to a curing station for curing of the concrete mixture. Stripping of the block is achieved by pushing it out of the mold with a stripper shoe which has a dual function. The stripper shoe is used during pre-consolidation to compress the dry cast concrete mixture. After pre-consolidation, the stripper shoe is used for forcing the pre-consolidated block from the mold. To produce blocks with an embossed surface structure or pattern on the front face, the stripper shoe is provided on its dry cast mixture engaging face with a negative of the three-dimensional surface structure to be produced on the block face during pre-consolidation.
Stripping the pre-consolidated block by pushing it from the mold requires a clear path for the block through the mold, which mandates the use of movable mold walls in the manufacture of tapered, embossed blocks. To facilitate handling and stacking of pre-consolidated embossed blocks and especially to minimize damage to the embossed front face during curing, the embossed blocks are usually manufactured with the front and rear faces oriented up and down in the mold, respectively. That means the sidewalls of the mold must be movable from the angled position required for the shaping of the tapered shape of the block, in order to provide a clear path of the block through the mold. Thus, embossed wall blocks for the assembly of curved walls are desired which are more easily manufactured.
It is now an object of the invention to overcome at least one of the disadvantages associated with known dry cast embossed wall blocks.